osmosis. I predict that when the experiments takes place, the potato strip in the beakers with high sugar concentrations will shrink and lose mass

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Introduction

GCSE Biology Osmosis Coursework By Chatham South School Potato and Osmosis Investigation Introduction into Osmosis Osmosis is a unique type of diffusion. Diffusion is basically the movement of particles from areas where there are a groups of them to places where there are fewer a bit like someone releasing methane, you do not smell it straight it but it gradually spreads out then it is equally balanced having reached equilibrium Nice air Bad smell Osmosis is defined as the movement of water molecules from a region that they are highly concentrated to a region in which they are less concentrated. This movement only takes place through a partially permeable membrane such as a cell wall, which lets small molecules go through like water but does not let bigger molecules to pass through like sugar. The water molecules pass both ways. In this diagram, the water will more likely go right. Diagram of Osmosis Plant cells always have a strong cell wall surrounding them. When they obtain water by osmosis they commence to swell but the cell wall prevents them from bursting. If it were an animal cell, it would rupture because it does not have a cell wall. Plant cells become turgid when they are in dilute solutions. Turgid means inflated and firm. If these potato strips were placed in a solution with a low water concentration, then the opposite would happen. Water would shift out of the cell into the solution. ...read more.

Middle

To make sure that this experiment is safe I will take certain measures including: * wear goggles for the protection of my eyes * cover up any cuts * no running around the lab which may cause fatal accidents * if a spill has occurred make sure it has been cleaned straight away * be careful with the knife * also be careful with the borer * every stool, bags and coats be underneath the table * not to leave any experiments unattended Preliminary Method I will gather all equipment that will be needed for the experiment. Solutions - these are the solutions, which will be in each of the beakers. 1. 1 molar sugar solution with 200 ml of water 2. 0.75 molar sugar solution with 200 ml of water 3. 0.50 molar sugar solution with 200 ml of water 4. 0.25 molar sugar solution with 200 ml of water 5. Only pure water which consists of 200 ml of water Systematic Method 1. Using a knife, I will peel five potatoes 2. Using the borer, I will bore holes in the potato. 3. Using the scale, I will weigh the tubes and record it. 4. I will put all of the tubes in with the solutions at the same time. The time limit will be ten minutes. 5. In the end, I will take all the tubes out from beakers, remove excess water, and weigh. Results of Preliminary Method Solution Number Mass Before Grams Mass After Grams Percentage Change % 1 15.801 15.611 1.3 2 15.838 15.343 - 3.1 3 ...read more.

Conclusion

This would allow more osmosis to happen and I would be able to find the isotonic points of the experiments more accurately as the one I had made is very rough. For weighing of each potato piece, I could have measured it on a more accurate scale like 0.000 instead of 0.00 But I also may decide to change the plant tissue to a cucumber or carrot. One thing I found hard during the investigation was the cutting of the potato pieces, if one piece was different from the others then osmosis taking place in each piece may have been at different rates, as the surface area would have been affected. So to improve accuracy, I may try to use some sort of machine like a potato peeler and cutter from a fast food store. This would mean every potato piece would be the same mass making it a fairer test. Throughout the experiment, I used a measuring cylinder, which is not always precisely accurate. I could have used a burette or a titration. One other thing was that when I removed excess water from the potatoes after the experimentation, I might have removed more excess water than others. So in the future, I may find another answer to drying like a hair blow dryer. Overall, even though I may say so myself, the investigation of my main method was very successful. Also, I was pleased with the comparison between my prediction and main method. I had a number of results from which I was able to make very useful graphs. GCSE Biology Osmosis Coursework By Chatham South School ?? ?? ?? ?? 1 ...read more.

Related GCSE Life Processes & Cells essays

And there fore the weight should decrease, at least noticeable for us to notice. The difference between the water concentration in the potato and the 0.8 molar solution of sucrose is big, and the water in the potato should be transferred from the potato, through the permeable membrane, to the solution surrounding the potato.

My theory in this experiment is that, due to the difference in the water concentrations of the two substances, I believe that the weight of the potato will start decreasing when it is tested on 0.2 molar solutions of sucrose and greater.

This decrease was due to the flow of water out of the vacuole making the vacuole pull inwards, away from the cell wall meaning the cell was plasmolysed (flaccid). Thus the increase was due to the flow of water into the vacuole and the vacuole had begun to push against the cell wall, this is known as a turgid cell.

Four test tubes were used: one for each of the different solutions used. A chip was placed in each test tube and left for 30 minutes. After the 30 minutes, the chips were removed from the test tubes and their new lengths and changes in length were recorded.